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(Model) E. Tl STARR. 2Sheets-Sheet 1. Dental Engine Hand Piece.

No. 233,707. Patented Oct. 26, 1880.

(Model.) 2 Sheetssneet 2.

E. T. STARR.

.Dental Engine Hand Piece. v No. 233,707. Patented Oct. 26,1880.

N. PETERS, FI-lDTQ-LlrrloaimnmA WASHINGTON. D c.

Y ELIT. STARR, OFPHILADELPHIA, PA., ASSIGNOR TO JAS. W. WHITE, J.

'CLARENCE VHITE, AND H. M. LEWIS, AS TRUSTEES, OF SAME PLACE.

DENTAL-ENGINE HAN D-PIEC E.

SPECIFICATION forming part of Letters Patent No. 233,707, dated October26, 1880.

Application filed August 16, 1880. (Model.)

To all whom t may concern:

Be it known that I, ELI T. STARR, ot the city and county ofPhiladelphia, in the State of Pennsylvania, have invented certain newand useful Improvements in Dental-Engine Hand-Pieces, (Case H,) of whichthe following is a specification.

Myinvention relates to dental-engine handpieces which arecapable ofbeing grasped by the hand to guide and direct the operatingtool drivenby a rotary spindle-chuck mounted in the hand-piece casing.

The objects of my invention are to improve the construction andorganization of such hand-pieces, to the end that wear of the chuck andits bearings may be compensated; that the tool-locking devices may bereadily manipulated by the same hand that grasps the hand-piece in orderto release a tool from or lock it in Ithe chuck-socket, and that loosemotion or rattling of the, tools in the chuck may be avoided.

The subject-matter claimed is particularly pointed ont at the close ofthe specification.

In the accompanying drawings, Figure l is a longitudinal central sectionthrough the hand-piece. Fig. 2 is a cross-section therethrough on theline 2 2 of Fig. l; and Figs. 3 to l0, inclusive, are views oftoolshanks adapted for use with a hand-piece embodying my improvements.

The casing A of the hand-piece is a sec- -tional one, as usual,consisting, in the present example, of four tubular sections, a a a2 a3.The section a is the handle-section, and it affords bearing for thefront end of the rotary spindle tool-holder or chuck B. Saidhandlesection surrounds the tool-holder and forms a sheath for it, andis ordinarily held centrally of the fingers and thumb of the operator(somewhat after the fashion of holding a pen or pencil) in directing,guiding, and holding the operating-tooljo its work. Said handlesectionis connected with the tubular section a by screw-threads, so as to bedetachable for oiling, 85o., and said section a constitutes the rearaxial bearing of the spindle tool-holder, said tool-holder beingconnected at its buttend with aflexible power-conveyer, as usual,

tion on its longitudinal axis in the said bearings in the hand-piececasing. Casing-section ais connected with section a2 by screw-threads,so as to be readily separable, while the shanksection a4 is connectedwith said section a3 by a swivel-joint ot' well-known construction, sothat the handle-section, which is grasped by the operator, ina-y turn orswivel around the tool-holder relatively to said shank-section toconform to the turning movements ofthe hand, and this withoutinterfering with the free rotation oi' said tool-holder in its bearings.The said shank-section is connected with a iiexible tubular sleeve orcover, which envelops the iiexible power-conveyer, so as to form asheath for said conveyer, within which it may freely rotate. The saidiiexible shaft and sheath may be substantiallylike those shown in Stowsreissued Letters Patent No. 8,607, of March 4, 1879.

An annular collar, b, is formed upon the tool-holder, and this collarbears upon a loose hard-metal friction-ring, c, (of which there may betwo or 1nore,) interposed between said collar and the annular shoulderformed by the front end of the casing-section a', whereby said collarconstitutes the thrust or push bearing of the tool-holder, and preventsinward endwise movement of said holder in the casing when a pushorthrust cut is being made with the operating-tool.

In order to prevent endwise outward movement of the tool-holder in thecasing when a pulling or draw cut is being made with the operating-tool,I preferably form the front end ot' the tool-holder with a taperingbearing-surface fitting the correspondingly-shaped bearingin thehandle-section of the casing. Such a tapering bearing also compels thechuck to run smoothly, and affords means for readily compensating forwear of the chuck and bearings by adjusting or screwing up the sectionsa a ofthe casing.

I also provide the tool-holder at its rear end with an adjustablecollar, d, of hard metal, and this collar may constitute thepull-bearing by abutting against the annular shoulder formed by the rearend of the casing-section c', and thus save the effect of wear on thefront tapering bearing of the tool-holder at the nose of the hand-piece.

I do not claim herein, however, any of the devices so far described, nordo I claim the annular space c at the front end ofthe casing in advanceofthe front end of the tool-holder B, which is for the purpose ofpreventing the escape of lubricating-oil to the outside of thehand-piece, and also to prevent access of saliva, &c., taken up by theoperating-tool, to the bearings ofthe tool-holder, as such is theinvention of one Phillips, heretofore patented.

The front end of the tool-holder is socketed, as usual, for thereception of the driving-ends ofthe operating-tools; but this socket inthis example is a peculiar one, in that it tapers from its largest partat the mouth inwardly, while the shank of the operating-tool iscorrespondingly tapered, so as to t snugly in the said socket. The saidtool-shank is provided with a driving-surface,f, which engages with anactuating surface or pin, h, extending into or across the tool-socket,whereby the tool is positively driven with the tool-holder, and is alsoprovided with a notch or groove, f', for the engagement of thetool-locking device, which prevents endwise movement or disengagement ofthe tool. Said tool-lock consists, preferably, of a stiff or rigidsliding latch or tumbler, G, fitted in a longitudinal groove in thetool-holder, and connected with a ring or annulus, H, encircling saidholder, and capable of sliding thereon while compelled to rotatetherewith. A spiral spring, I, encircling the tool-holder, is compressedbetween said sliding ring H and a iixed collar or annular shoulder, i,of the tool-holder, and the force or tension of this spring is alwaysexerted to force the ring H, and with it the latch G, backward, so as todepress the beak or hook g of the front goose-necked end of said latchG, which rides under the fixed collar i, into engagement with thelocking-notch f of the toolshank, thereby locking said shank in thesocket and exerting a drawing action thereon, so as to keep said shankin the tapering socket with a close fit, thus preventing lateral motionor rattling of the tool in the socket.

In order to disengage the locking end of the latch from thelocking-notch of the tool-shank, (should one bein the socket oftheholder,) to permit of the withdrawal of the tool, or to permit theinsertion of a different tool in the holder, I provide the front edge ofthe hooked end g of the locking-latch with an inclined or wedgedsurface, gso that when the latch is moved forward said inclined surfaceg' will ride upon a similar surface, g2, in the toolholder, and beforced or wedged upward, the upward movement of the latch beingpermitted by cutting away a portion of its upper edge, as at g3, underthe fixed collar t' of the tool-holder. The latch is also provided withan abrupt shoulder, g4, so that the latch when forced forward not onlyrides its hooked end g out of contact with the tool-shank, but forcessaid tool outward or loosens it by its shoulder g4 coming against theend of the tool. By this mode of construction I overcome the objectionheretofore existing to the use ot' tapering shanked tools withdentalengine hand-pieces-that is, I prevent the wedging or sticking ofthe tool in the socket of the holder by forcing it positively out orlooseningit.

In order to place the latch under the control ot the hand that holds andguides the hand-piece in operation, so that but one hand is required tohold the hand-piece and operate the tool-lock, I pivot a lever, J,externally upon the casing, the rear end of which lever is provided witha hook or nose,j, adapted, when the lever is raised from its positionparallel with the casing, to entera slot, a4, in said casing, and engagethe rear side of the sliding ring H, so as to move said ring forward andcarry with it the slidinglatch, to.

move said latch from its locking position, as before explained. n

It will be understood, of course, that as the lever is rocked from frontto rear the hook j will travel around the pivot or fulcrum of the leverto carry the latch forward.

A light plate-spring, k, acts upon the lower edge of the lever to holdit down closely to the casing when not rocked by the finger, while thespiral spring I throws thelatch into its locking position to draw thetool rmly in the socket and lock it from endwise movement as soon as thepressure upon the lever is removed and said lever allowed to assume itsnormal position, as shown in Fig. 1.

I have shown inFigs. 3 to l0, inclusive, several forms of tool-shanksfor hand-pieces embodying my improvements.

In Figs. 5 and 8, instead of shanks having a tapering surface to fit acorresponding socket, I have shown shanks having straight cylindricalportions of different diameters. For such shaped shanks the toolholdersocket will be correspondingly formed.

In Fig. l, I have also shown the operatingtool as formed in sections,the portion carrying the operating-point tting in a socket of the shankproper, the two sections being united by a through-pin or some suchfastening.

I disclaim herein in favor of my application filed July 29, 1880, anypatentable subjectmatter common to the two cases.

I claim as my inventionl. The combination, substantially as hereinbeforeset forth, of the hand-piece casing, the spindle tool-holder turning inbearings therein, the rigid sliding tool-locking latch, the spring tomove said latch in one direction to exert a drawing action upon thetool-shank and lock said shank in the tool-holder socket, and the leverpivoted upon the casing so as to lie parallel therewith and be capableof a rockin gmotion fromfront to rear, and the hand- IOO IOS

piece to move the latch and release it from engagement with thetool-shank.

2. The combination, substantially as hereinbefore set forth, of thehand-piece casing, the spindle tool-holder turning in bearings therein,the fixed collar or shoulder on said holder, and the sliding latchmovable in a recess in the tool-holder beneath said collar, and having aportion of its upper edge cut away to permit the front end of the latch,when forced forward, to rise laterally in the recess to disen gage itfrom the tool-shank.

3. The combination, substantially as hereinbefore set forth, of4 thehand-piece casing, the spindle tool-holder turning in bearings in saidcasing, the sliding tool-lookin g latch provided with a beak at itsfront end to engage a ELI T. STARR.

Vitnesses:

WM. J. PEY'roN, J AMES YOUNG.

It is hereby certified that in Letters Patent No. 233,707, dated October26, 1880, to Eli T. Starr, for Dental Engine Hand Piece, iu line 132page 2 of the specification forming part of said Letters Patent, afterthe word rear 2o comme and the word and were erroneously inserted, andthe word of was erroneously omitted; that the proper corrections havebeen made in the records of this Oee, and

thaty said correction is hereby iliade in the Letters Patent.

Signed, conntersigned, and sealed this 30th day of October, A. D. 1880.

[SEAL] C. SCHURZ,

Secretary of the Inter/01. Countersigned E. M. MARBLE, Commissioner ofPatents.

